Add support for automake 1.14
gnome-autogen.sh: Use autoreconf

instead autopoint/libtoolize/autoconf/automake manually
macros2/gnome-autogen.sh: Create m4 directory if it doesnt exits

This is a automake bug fixed in automake 1.13.2
gnome-autogen: Do not use sed to get the AC_CONFIG_MACRO_DIR directory
Rename configure.in to configure.ac
gnome-autogen.sh: Check only for autoreconf

autoconf, automake, libtool, gettext are already checked by autoreconf
gnome-autogen.sh: run glib-gettexize if using GLib gettext

This code was removed by error in
commit 323bbfe0989405725379cada1aa5cb361fd2999f